Since its advent, transesophageal echocardiography (TEE) has played an important role in the surgical management of patients undergoing mitral valve (MV) surgery. Mitral regurgitation (MR) assessment and surgical decision making remains one of the most challenging situations, especially when considered in the context of ischemic heart disease or when associated with another dominant lesions. Techniques for MV repair are becoming more and more intricate with outcome studies strongly supporting repair in contrast to replacement in patients with primary MV pathology. It is in these scenarios that a comprehensive intraoperative TEE is invaluable. Once MR is detected, it is vital to assess the valve for both qualitative and quantitative features. The following text discusses the approach, challenges and value of intraoperative TEE in the assessment of MR.